CMP Pad Temperature Control Using Evaporative Cooling Nozzles
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Solution Overview
Problem
Conventional CMP apparatuses struggle to precisely control the polishing rate of substrates due to variations in polishing pad temperature, which affects the chemical action of the polishing liquid, and there is a need for rapid temperature adjustments to improve in-plane uniformity and precision.
Innovation Solution
A polishing apparatus equipped with a pad-temperature regulating system using cooling nozzles that inject a cooling agent with a boiling point lower than atmosphere temperature, combined with gas nozzles to vaporize the cooling agent quickly, and a heater to control the polishing pad temperature, allowing for precise temperature regulation and rapid adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling methods are used to decrease pad temperature, then pad temperature can be reduced, but the temperature reduction is slow and cannot reach below ambient temperature efficiently
Solution Approach 1:
The patent utilizes the phase transition (evaporation) of cooling liquid through gas nozzles to achieve rapid heat absorption and temperature reduction. The cooling liquid is sprayed onto the polishing pad and rapidly evaporates, absorbing latent heat of vaporization and quickly decreasing the pad temperature to below ambient temperature levels.
Solution Approach 2:
The patent employs gas nozzles to deliver cooling liquid under pressure onto the polishing pad surface. This pneumatic delivery system enables controlled, high-velocity spray application that enhances evaporation rate and cooling efficiency, allowing rapid temperature reduction that conventional contact cooling methods cannot achieve.
2Manufacturing precision
If pad temperature is decreased to improve in-plane uniformity, then polishing precision improves, but the chemical action of polishing liquid is reduced due to lower temperature
Solution Approach 1:
The patent applies cooling locally to specific regions of the polishing pad through strategically positioned gas nozzles. This localized cooling approach creates temperature gradients that can be optimized to maintain adequate polishing rate in certain areas while achieving the required in-plane uniformity in critical regions, balancing precision and productivity.
Solution Approach 2:
The patent implements periodic or intermittent cooling cycles rather than continuous cooling. The cooling liquid is sprayed in controlled pulses or cycles, allowing the pad temperature to fluctuate within an optimal range that maintains both sufficient chemical action for polishing rate and adequate cooling for in-plane uniformity.
3Temperature
If cooling liquid is sprayed onto polishing pad, then rapid cooling is achieved, but the polishing liquid supply is interfered with and polishing quality may deteriorate
Solution Approach 1:
The patent segments the cooling and polishing liquid delivery systems into separate, independently controlled channels. Gas nozzles for cooling liquid delivery are positioned and configured to spray cooling fluid in a manner that does not interfere with the separate polishing liquid supply system, allowing both functions to operate simultaneously without compromising polishing quality.
Solution Approach 2:
The patent uses the polishing pad itself as an intermediary medium that receives both cooling liquid and polishing liquid. The pad absorbs and distributes the cooling liquid while maintaining its polishing surface properties, acting as a mediator that enables rapid cooling without directly interfering with the polishing liquid's chemical action on the substrate.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables precise control of the polishing rate by quickly decreasing the pad temperature, improving in-plane uniformity and precision of substrate polishing, and extending the temperature control range beyond conventional methods.
Implementation Method 1
at least one cooling nozzle configured to inject a cooling agent onto the polishing surface
Implementation Method 2
the cooling agent has a boiling point lower than atmosphere temperature
Implementation Method 3
at least one gas nozzle configured to inject dry gas onto the polishing surface
Implementation Method 4
a pad-temperature regulating apparatus for regulating the temperature of the polishing surface
Data Source
AI summary
A polishing apparatus is disclosed, which can precisely control a polishing rate by quickly decreasing a pad temperature to below ambient temperature. The polishing apparatus includes a rotatable polishing table supporting a polishing pad; a polishing head configured to press a substrate W against a polishing surface of the rotating polishing pad to polish the substrate; at least one pad-temperature measuring device configured to measuring a temperature of the polishing surface; a pad-temperature regulating apparatus for regulating the temperature of the polishing surface; and a controller configured to control operation of the pad-temperature regulating apparatus based on the temperature of the polishing surface measured by the at least one pad-temperature measuring device. The pad-temperature regulating apparatus includes: at least one cooling nozzle configured to inject a cooling agent onto the polishing surface; and at least one gas nozzle configured to inject dry gas onto the polishing surface. The cooling agent has a boiling point lower than atmosphere temperature.